Pesticides, including fungicides, are often categorized as “site specific” or “multi-site”, describing how they interact with the target organism. Site specific products are typically just that – they disrupt a very specific pathway or function in the target organism. Multi-site products typically disrupt several pathways and functions.
Site-specific products are often favored in conventional agriculture due to their reduced impact on off-target organisms. However, because of their specificity, the likelihood that an individual in a population has a mutation that can reduce its sensitivity to that fungicide type is high. When those mutated individuals build up in a population, typically as a result of repeated applications of those same site-specific fungicides, this can result in “field level” control failure of a disease.
Fungicide stewardship is an all-encompassing term that focuses on principles and practices that mitigate field-level disease control failures by reducing the selection pressure and population build-up of resistant pathogens. Other disease control strategies that limit the size of the pathogen population also indirectly reduce the likelihood of a field-level control failure in a disease management program.